The new GY-HM790 adds SD recording, Genlock In, TC IN/OUT with
optional KA790 Studio Adapter, VF-HP790 8.4" Studio Viewfinder, 26-pin
multicore module, CCU, fiber remote module & a local remote panel.

Full details of the press release plus discussion are underway here:

http://www.dvinfo.net/forum/jvc-gy-hm-700-series-camera-systems/476206-jvc-announces-gy-hm790-new-studio-adapter-viewfinder.html